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991.
992.
Mingxuan Mao Li Zhang Qichang Duan O.J.K Oghorada Pan Duan Bei Hu 《International Journal of Green Energy》2017,14(8):694-702
The power-voltage (P-V) characteristic curves of a PV array are nonlinear and have multiple peaks under partially shaded conditions (PSCs). This paper proposes a novel maximum power point tracking (MPPT) method for a PV system with reduced steady-state oscillation based on a two-stage particle swarm optimization (PSO) algorithm. The grouping method of the shuffled frog leaping algorithm (SFLA) is incorporated in the basic PSO algorithm (PSO-SFLA), ensuring fast and accurate searching of the global extremum. An adaptive speed factor is also introduced into the improved PSO to further enhance its convergence speed. Test results show that the proposed method converges in less than half the time taken by the conventional PSO method, and the power is improved by 33% under the worst PSCs, which confirms the superiority of the proposed method over the standard PSO algorithm in terms of tracking speed and steady-state oscillations under different PSCs. 相似文献
993.
Guangna Xie Yu Chen Ke Bei Zhipeng Gao Mingde Yang Junliang Wang 《International Journal of Green Energy》2017,14(11):861-867
A fused silica capillary reactor combined with a heating/cooling stage, a microscope and a digital camera were used to investigate phase behavior during the hydrothermal liquefaction of microalgae (Dunaliella tertiolecta) and model compounds, including soya protein and glycine, starch, glucose and xylose, stearic acid and palmitic acid. Bubbles were generated at 246°C and disappeared at 360°C upon heating when Dunaliella tertiolecta used as feedstocks. Moreover, liquid products were generated at 300°C upon heating and oily liquid products began to separate out at 250°C upon cooling. The phase behavior of soya protein was similar to that of the Dunaliella tertiolecta. Meanwhile, there only observed the bubbles generation during hydrothermal liquefaction of glycine. Heating the starch, glucose and xylose above 350°C generated black solids from carbonization. Stearic acid and palmitic acid only had the process of melting, dissolution, dispersion and precipitation. 相似文献
994.
Aditi Banerji V. V. N. Kishore Malini Balakrishnan 《International Journal of Green Energy》2017,14(6):522-527
Dilute acid pretreatment and steam pretreatment were evaluated for maximum sugars release and ethanol production from sweet sorghum bagasse (SSB). The fermentation potential of the condensate and hydrolysate obtained from steam pretreatment (10 kg/cm2, 10 minutes) and dilute acid hydrolysis (1% (w/w) sulphuric acid, 25% substrate loading) respectively, was checked with Pichia stipitis NCIM 3497 and Debaryomyces hansenii sp. Ethanol production and yield using acid hydrolysate was higher with Debaryomyces hansenii sp. (28.4 g/L and 0.37 g/g respectively) as compared with Pichia stipitis NCIM 3497 (21.9 g/L and 0.29 g/g respectively). 相似文献
995.
996.
Yuan-Na Xing Ying Guo Mei Xie Ru-Lang Shen 《Environmental pollution (Barking, Essex : 1987)》2009,157(4):1382-1387
A solid-phase microextration-based sampling method was employed to determine the concentrations of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its metabolites, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethene (DDE) and 1-chloro-2,2-bis(p-chlorophenyl)ethene (DDMU), in two estuarine bays, Daya Bay and Hailing Bay, of South China. Six DDT components including p,p′-DDT, o,p′-DDD, p,p′-DDD, o,p′-DDE, p,p′-DDE, and p,p′-DDMU were detected in Hailing Bay, while only p,p′-DDD was found in Daya Bay. p,p′-DDD was the most abundant DDT component in both bays, sharply different from the previous finding in the water column of the Palos Verdes Shelf, California, USA that p,p′-DDE was prevalent. In addition, the occurrence of p,p′-DDMU (with a range of 0.047-0.21 ng/L in Hailing Bay) has not been reported around the globe, and its presence in our study region appeared to stem from dehydrochlorination of p,p′-DDD, favored under aerobic conditions, but further investigations are clearly needed to confirm the mechanism for generation of DDMU in estuarine environments. 相似文献
997.
Part V—sorption of pharmaceuticals and personal care products 总被引:5,自引:0,他引:5
Background, aim, and scope Pharmaceuticals and personal care products (PPCPs) including antibiotics, endocrine-disrupting chemicals, and veterinary pharmaceuticals
are emerging pollutants, and their environmental risk was not emphasized until a decade ago. These compounds have been reported
to cause adverse impacts on wildlife and human. However, compared to the studies on hydrophobic organic contaminants (HOCs)
whose sorption characteristics is reviewed in Part IV of this review series, information on PPCPs is very limited. Thus, a
summary of recent research progress on PPCP sorption in soils or sediments is necessary to clarify research requirements and
directions.
Main features We reviewed the research progress on PPCP sorption in soils or sediments highlighting PPCP sorption different from that of
HOCs. Special function of humic substances (HSs) on PPCP behavior is summarized according to several features of PPCP–soil
or sediment interaction. In addition, we discussed the behavior of xenobiotic chemicals in a three-phase system (dissolved
organic matter (DOM)–mineral–water). The complexity of three-phase systems was also discussed.
Results Nonideal sorption of PPCPs in soils or sediments is generally reported, and PPCP sorption behavior is relatively a more complicated
process compared to HOC sorption, such as the contribution of inorganic fractions, fast degradation and metabolite sorption,
and species-specific sorption mechanism. Thus, mechanistic studies are urgently needed for a better understanding of their
environmental risk and for pollution control.
Discussion Recent research progress on nonideal sorption has not been incorporated into fate modeling of xenobiotic chemicals. A major
reason is the complexity of the three-phase system. First of all, lack of knowledge in describing DOM fractionation after
adsorption by mineral particles is one of the major restrictions for an accurate prediction of xenobiotic chemical behavior
in the presence of DOM. Secondly, no explicit mathematical relationship between HS chemical–physical properties, and their
sorption characteristics has been proposed. Last but not least, nonlinear interactions could exponentially increase the complexity
and uncertainties of environmental fate models for xenobiotics. Discussion on proper simplification of fate modeling in the
framework of nonlinear interactions is still unavailable.
Conclusions Although the methodologies and concepts for studying HOC environmental fate could be adopted for PPCP study, their differences
should be highly understood. Prediction of PPCP environmental behavior needs to combine contributions from various fractions
of soils or sediments and the sorption of their metabolites and different species.
Recommendations and perspectives More detailed studies on PPCP sorption in separated soil or sediment fractions are needed in order to propose a model predicting
PPCP sorption in soils or sediments based on soil or sediment properties. The information on sorption of PPCP metabolites
and species and the competition between them is still not enough to be incorporated into any predictive models. 相似文献
998.
Vinicius F. Farjalla André M. Amado Albert L. Suhett Frederico Meirelles-Pereira 《Environmental science and pollution research international》2009,16(5):531-538
Background, aim, and scope Dissolved humic substances (HS) usually comprise 50–80% of the dissolved organic carbon (DOC) in aquatic ecosystems. From
a trophic and biogeochemical perspective, HS has been considered to be highly refractory and is supposed to accumulate in
the water. The upsurge of the microbial loop paradigm and the studies on HS photo-degradation into labile DOC gave rise to
the belief that microbial processing of DOC should sustain aquatic food webs in humic waters. However, this has not been extensively
supported by the literature, since most HS and their photo-products are often oxidized by microbes through respiration in
most nutrient-poor humic waters. Here, we review basic concepts, classical studies, and recent data on bacterial and photo-degradation
of DOC, comparing the rates of these processes in highly humic ecosystems and other aquatic ecosystems.
Materials and methods We based our review on classical and recent findings from the fields of biogeochemistry and microbial ecology, highlighting
some odd results from highly humic Brazilian tropical lagoons, which can reach up to 160 mg C L−1.
Results and discussion Highly humic tropical lagoons showed proportionally lower bacterial production rates and higher bacterial respiration rates
(i.e., lower bacterial growth efficiency) than other lakes. Zooplankton showed similar δ13C to microalgae but not to humic DOC in these highly humic lagoons. Thus, the data reviewed here do not support the microbial
loop as an efficient matter transfer pathway in highly humic ecosystems, where it is supposed to play its major role.
In addition, we found that some tropical humic ecosystems presented the highest potential DOC photo-chemical mineralization
(PM) rates reported in the literature, exceeding up to threefold the rates reported for temperate humic ecosystems. We propose
that these atypically high PM rates are the result of a joint effect of the seasonal dynamics of allochthonous humic DOC input
to these ecosystems and the high sunlight incidence throughout the year. The sunlight action on DOC is positive to microbial
consumption in these highly humic lagoons, but little support is given to the enhancement of bacterial growth efficiency,
since the labile photo-chemical products are mostly respired by microbes in the nutrient-poor humic waters.
Conclusions HS may be an important source of energy for aquatic bacteria in humic waters, but it is probably not as important as a substrate
to bacterial growth and to aquatic food webs, since HS consumption is mostly channeled through microbial respiration. This
especially seems to be the case of humic-rich, nutrient-poor ecosystems, where the microbial loop was supposed to play its
major role. Highly humic ecosystems also present the highest PM rates reported in the literature. Finally, light and bacteria
can cooperate in order to enhance total carbon degradation in highly humic aquatic ecosystems but with limited effects on
aquatic food webs.
Recommendations and perspectives More detailed studies using C- and N-stable isotope techniques and modeling approaches are needed to better understand the
actual importance of HS to carbon cycling in highly humic waters. 相似文献
999.
Jan Bernd Barhorst Roland Kubiak 《Environmental science and pollution research international》2009,16(5):582-589
Background, aim and scope The use of sodium hypochlorite (HYP) in viticulture results in effluents which are contaminated with halogenated substances.
These disinfection by-products (DBPs) can be quantified as group parameter ‘adsorbable organic halogens’ (AOX) and have not
been determined in effluents of viticulture yet. The substances that are detected as AOX are unknown. The AOX can be composed
of harmless substances, but even toxic contaminants. Thus, it is impossible to assess ecological impacts. The aim of this
study is to determine the quantification of AOX and DBPs after the use of HYP. This will be helpful to reduce environmental
pollution by AOX.
Materials and methods The potential of HYP to generate AOX was determined in laboratory-scale experiments. Different model solutions were treated
with HYP according to disinfection processes in viticulture and conditions of AOX formation in effluents were simulated. AOX
were quantified using the flask-shaking method and identified DBPs were investigated by gas chromatography–mass spectrometry.
Results Treatment with HYP resulted in the formation of AOX. The percentage conversion of HYP to AOX was up to 11%. Most important
identified DBPs in viticulture are chloroform, dichloroacetic acid and trichloroacetaldehyde. In addition, the formation of
carbon tetrachloride (CT), 1,1,1-trichloropropanone, 2,4-dichlorobenzoic acid and 2-chloro-/2,4-dichlorophenylacetic acid
was investigated. It was demonstrated that reaction temperature, concentration of HYP and type of organic matter have important
influence on the formation of chlorinated DBPs.
Discussion The percentage conversion of HYP to AOX was similar to other published studies. Although a correlation of single compounds
and AOX is difficult, chloroform was the predominant AOX. Generation of the volatile chloroform should be avoided due to possible
adverse effects. The generation of dichloroacetic acid is of minor importance on account of biodegradation. Trichloroacetaldehyde
and 1,1,1-trichloropropanone are weak mutagens and their formation should be avoided.
Conclusions The generation of AOX and chlorinated DBPs can be minimised by reducing the concentrations of the organic materials in the
effluents. The removal of organic matter before disinfection results in a decreased formation of AOX. HYP is an effective
disinfectant; therefore, it should be used at low temperatures and concentrations to reduce the amount of AOX. If possible,
disinfection should be accomplished by the use of no chlorine-containing agents. By this means, negative influences of HYP
on the quality of wine can also be avoided.
Recommendations and perspectives Our results indicate that HYP has a high potential to form AOX in effluents of viticulture. The predominant by-products are
chloroform, dichloroacetic acid and trichloroacetaldehyde. In further research, wastewaters from a winery and the in- and
outflows of two sewage treatment plants were sampled during vintage and analysed. These results will be discussed in a following
paper. 相似文献
1000.
Tobias Frische Michael Faust Wiebke Meyer Thomas Backhaus 《Environmental science and pollution research international》2009,16(5):593-603